1. Field of the Invention
The present invention relates to a cover member of a light scanning apparatus to be used in an image forming apparatus.
2. Description of the Related Art
As an electrophotographic image forming apparatus, a copying machine, a printer, a facsimile, and a multi-function device of those machines are exemplified. As a light scanning apparatus to be used in an image forming apparatus, a light scanning apparatus having the following configuration has been known. That is, the light scanning apparatus forms an electrostatic latent image on a photosensitive member in such a manner that a rotary polygon mirror deflects a light beam emitted from a light source, and an optical component such as a lens and a mirror guides the deflected light beam onto a photosensitive surface of the photosensitive member.
An overview of components of a generally adopted related-art light scanning apparatus will be described below. A semiconductor laser device is provided in a light source portion, and a circuit board connected to the light source portion is arranged on an outer side of a side wall of a housing. The circuit board is fixed on the housing with a screw, a spring member, or an adhesive. On the circuit board, a variable volume is fixed. The variable volume adjusts a light intensity of a light beam emitted from the light source portion to a light intensity corresponding to characteristics of the image forming apparatus. The variable volume is adjusted when initializing the apparatus at the time of assembly of the apparatus in a factory. The variable volume is adjusted to a default value, and thus a default light intensity of the light beam corresponding to the characteristics of the image forming apparatus is determined. With reference to the default light intensity, the light intensity of the light beam at the time of image formation is controlled.
At the time of assembly of the light scanning apparatus, at the time of transportation of the light scanning apparatus, and at the time of operation of mounting the light scanning apparatus into the image forming apparatus, a hand and cloth of an operator, a packing material for transportation, or a component provided at a periphery of the light scanning apparatus may be sometimes brought into contact with a control circuit board. In this case, setting of the variable volume provided on the circuit board is fluctuated, and thus the default value may be deviated. As a result, such image failure occurs that density of an output image is light or dark. Adjustment by the variable volume needs a dedicated jig capable of high-precision measurement. In a case where the variable volume is deviated from the default value after the light scanning apparatus is mounted in the image forming apparatus, the following problem arises. Normally, the light scanning apparatus is assembled in a clean room in which a dust amount in the air is controlled or in an environment approximate to the clean room. In a case where the variable volume is changed, in order to correct the default light intensity of the light beam, after cleaning the light scanning apparatus, the light scanning apparatus needs to be brought again into an assembly line for the light scanning apparatus so that the assembly operation of the apparatus may consume a lot of time.
To address the above-mentioned problem, in Japanese Patent Application Laid-Open No. 2009-265503, there is proposed a configuration in which, in addition to a main cover configured to protect an inside of the light scanning apparatus from contamination, a protection member configured to cover the circuit board is provided. Further, there is also proposed a configuration in which a projecting portion is formed on a part of the main cover and the projecting portion covers the circuit board.
However, in the configuration disclosed in Japanese Patent Application Laid-Open No. 2009-265503 in which the protection member is provided, a step of mounting a member configured to cover the circuit board is required in assembling steps, and hence the operation may be complicated. Meanwhile, in the configuration in which the projecting portion is formed on the part of the main cover, complicated operation is not caused, but the following problem arises. That is, the projecting portion formed on the cover member disables stable stacking of a plurality of cover members, and hence efficiency of conveying the cover members in a factory is reduced.